It turns out that `string split0` didn't actually ever do any
splitting. The arg_iterator_t already split stdin on NUL, and split0 just
performed an additional search that could never succeed (since
arguments from argv already can't contain NUL).
Let the arg_iterator_t not perform any splitting if asked, and then
let split0 split in 0.
One slight wart is that split0 ignores a trailing NUL, which normal
split doesn't.
Fixes#5701.
This adds a new string command split0, which splits on zero bytes.
split0 has superpowers because its output is not further split on
newlines when used in command substitutions.
We need a way to encode arbitrary strings into valid fish variable
names. It would also be nice if we could convert strings to valid URLs
without using the slow and hard to understand `__fish_urlencode` function.
In particular, eliminating the need to manipulate the locale.
Fixes#4150
Per discussion in PR#3998 to review adding a `--filter` flag to `string
replace` rename the same flag in the `string match` subcommand to avoid
confusion about the meaning of the flag.
pcre2_substitute() now sets the output buffer length to PCRE2_UNSET (~0)
if the output buffer is determined to be too small. This change keeps
track of the buffer size separately where pcre2 can't touch it.
A better fix would be to let pcre2 tell fish what size buffer it needs.
This can be done with PCRE2_SUBSTITUTE_OVERFLOW_LENGTH, but this
requires pcre2 10.21 or later (released January 12), which may be too
new to introduce as a dependency at this point.
Fixes#2743
